AC machines are extensively used in loaders or other heavy equipment machinery because they provide a higher efficiency than DC machines. Of the AC machines, an IPM machine has a high drive efficiency wide operating speed range for constant power region. An IPM machine controller also called an inverter, controls operation of the IPM machine. The controller produces ac control signals which are applied to the terminals of the IPM machine. Typically the controller controls the IPM machine based on information or a portion of information characterizing the IPM machine. At least part of the characterization refers to the operational model of the IPM machine that permits translation of input requests into desired operational output. For example, a desired output torque may be requested, and based on part of the characterization, the controller controls the IPM machine to deliver the desired torque. In order to provide the desired output torque, the IPM controller outputs operating points to the IPM machine in response to a desired torque.
One conventional method uses theoretical equations to find machine operating points, which may not be accurate. Another conventional method utilizes finite element analysis to find correct operating points, which is very time consuming. In addition, these conventional methods may not cover the full operating range in terms of speed and torque level.